While congestive heart failure in diabetes mellitus is common, its explanation on the basis of obstructive large or small coronary vessel disease is inadequate. This project was designed to closely examine contractile function of muscle removed from diabetic heart which include study of the processes of activation, contraction, relaxation and compliance in order to determine the presence or absence of a diabetic cardiomyopathy. Structural and ultrasturctural investigation of diabetic heart muscle will provide important structural correlation to the mechanical studies. The effect of duration of the hyperglycemia and its treatment with insulin as well as related phenomena such as hyperlipoproteinemia on contractile behavior of cardiac muscle will be assessed. This study, then, will help provide a more rational approach to the understanding of myocardial hypofunction or failure in human diabetes and its relation to control of the hyperglycemia.